4-Amino-3-hydroxynaphthalene-1-sulfonic acid diazo, and 3-Methyl-1-phenyl-1H-pyrazol-5(4H)-one coupling, a single accidentally nitrogen compounds; 2-Aminobenzoic acid diazo, and Naphthalen-2-ol coupling, another single accidentally nitrogen compounds, and then turn it into 1:2 chromium complex.